On Sun, Jul 17, 2016 at 7:59 PM, Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> wrote:
> Hi Kees,
>
> Today's linux-next merge of the kspp tree got a conflict in:
>
> arch/arm64/include/asm/uaccess.h
>
> between commit:
>
> bffe1baff5d5 ("arm64: kasan: instrument user memory access API")
>
> from the arm64 tree and commit:
>
> b19e7f50f056 ("arm64/uaccess: Enable hardened usercopy")
>
> from the kspp tree.
>
> I fixed it up (see below) and can carry the fix as necessary. This
> is now fixed as far as linux-next is concerned, but any non trivial
> conflicts should be mentioned to your upstream maintainer when your tree
> is submitted for merging. You may also want to consider cooperating
> with the maintainer of the conflicting tree to minimise any particularly
> complex conflicts.
>
> --
> Cheers,
> Stephen Rothwell
>
> diff --cc arch/arm64/include/asm/uaccess.h
> index 5e834d10b291,1779cbdb7838..000000000000
> --- a/arch/arm64/include/asm/uaccess.h
> +++ b/arch/arm64/include/asm/uaccess.h
> @@@ -264,14 -276,14 +264,15 @@@ extern unsigned long __must_check __cle
>
> static inline unsigned long __must_check __copy_from_user(void *to, const void __user *from, unsigned long n)
> {
> + kasan_check_write(to, n);
> - return __arch_copy_from_user(to, from, n);
> + check_object_size(to, n, false);
> + return __arch_copy_from_user(to, from, n);
> }
>
> static inline unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n)
> {
> - check_object_size(from, n, true);
> + kasan_check_read(from, n);
> - return __arch_copy_to_user(to, from, n);
> + return __arch_copy_to_user(to, from, n);
If I'm reading correctly, this second fixup is wrong. It should read;
kasan_check_read(from, n);
check_object_size(from, n, true);
return __arch_copy_to_user(to, from, n);
(i.e. fix double space between "return" and "__arch_copy..." in both
chunks and add check_object_size() calls after the kasan calls in both
chunks.
-Kees
--
Kees Cook
Brillo & Chrome OS Security
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